Heat powered portable fluid heaters



Jan. 23, 1968 J. P. NORTON ETAL 3,365,133

HEAT POWERED PORTABLE FLUID HEATERS Filed Dec. 27, 1965 2 Sheets-Sheet 1I c I 4 /36 I Q F /6 /4 I fl r 35 3 ll 23 39/ 25 -39 /H Ll 27 INVENTORSJan. 23, 1968 J. P. NORTON ETAL 3,365,133,

HEAT POWERED PORTABLE FLUID HEATERS Filed Dec. 27, 1965 2 SheetsSheet 2I NVENTORS United States Patent 3,365,133 HEAT FOWERED PGRTABLE FLUIDHEATERS John P. Norton, St. Louis, and Harold L. Kirk, Kirirwood, Mo,assignors to American Air Filter Company, Inc., Louisville, Ky., acorporation of Delaware Filed Dec. 27, 1965, Ser. No. 516,641 7 Claims.(Cl. 237-7) ABSTRAT OF THE DISCLQSURE A self-contained heat poweredfluid heater having a motive fluid circulating system where the motivefluid is heated to drive a rotary engine to provide power for theapparatus and heat is transferred from the motive fluid to the fluid tobe heated. A bypass means is provided to bypass a portion of the motivefluid around the engine in response to the condition of the motivefluid.

Background of the invention Some previous portable fluid heaters haveincluded means, usually a burner, for heating the fluid as desired, anda separate power supply for auxiliary equipment which usually includes ameans for moving the fluid to be heated through the heater, a blower forsupplying combustion air to the burner, and a fuel pump to supply fuelto the burner. In most previous portable fluid heaters the separatepower supply has been an internal combustion engine or an electricmotor, both of which have certain inherent disadvantages when used insuch portable heaters.

Other previous heat-powered fluid heaters have not required a separatesource of power for the auxiliary equipment because the power has beenfurnished by a gas turbinedriven by exhaust gas from the fluid heatingmeans, usually a burner. In these previous heaters, the auxiliaryequipment has usually included blowers for moving the fluid to beheated, and a fuel pump to supply fuel to the burner. In such previousgas turbine-powered, fluid heaters it has also been necessary to providean air compressor to furnish compressed combustion air to the burnerupstream of the turbine. The compressors in such previous heat-poweredfluid heaters which have been driven by the turbine are necessarilycomplex and consume a significant amount of the power generated by theburner. In addition to wasting a great deal of power in compressingcombustion air, such heaters are ineflicient because a significantportion of the work done in compressing combustion air is lost when thehot, compressed combustion gases are exhausted from the heat exchangesystem. The air compressor also requires an increase in the size andcomplexity of the turbine required to furnish power to auxiliaryequipment. The over-all fuel efliciency of such heaters is dependent onthe efliciency of the turbine because it is required to operate the aircompressor. Also, in previous heaters where exhaust gas has been used todrive the turbine, the exhaust gas contains the products of combustionfrom the burner, is therefore corrosive, andcomplicates design of theturbine.

The present invention provides an eflicient and novel portableheat-powered fluid heater wherein a single motive fluid can be heated toprovide a source of power for auxiliary equipment, and to provideheating medium to the heat exchange system. Moreover, the new andadvantageous heater of the present invention eliminates the previouslyrequired power consuming combustion air compressor and permits the useof a straightforward, fluid responsive engine wherein work expended tocompress combustion air is not lost by exhausting the compressedcombustion air from a heat exchanger to the atmosphere.

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Furthermore, etflciency of the fluid-responsive engine of the presentinvention is not a significant factor in determining the fuel efficiencyof the heater because the motive fluid exhausted from the engine througha heat exchanger is not rejected, but is recycled within the system toprevent loss of heat to the atmosphere.

Various other features of the present invention will become obvious toone skilled in the art upon reading the disclosure set forthhereinafter.

In accordance with the present invention, an improved, heat-powered,portable fluid heater arrangement is provided to heat a desired fluidcomprising a motive fluid circulating system having a motive fluidsupply source; a heat source within said system to expand the motivefluid including a motive fluid inlet and a motive fluid outlet; afluid-flow responsive rotary engine in the system to provide powertoselected elements in the fluid circulating systern in response topassage of said motive fluid through the engine, the fluid flowresponsive engine including a fluid inlet communicating with the boileroutlet to receive motive fluid from the boiler, and a motive fluidoutlet to exhaust motive fluid from the engine; power output meanscooperatively joined to the engine to transmit useful power resultingfrom the motive fluid passing through the engine to provide power asdesired for the heater; heat exchange means in the system to transferheat from the motive fluid to the fluid to be heated, including a firstinlet to receive motive fluid communicating with the motive fluid outletof the engine, to receive motive fluid, a first fluid outlet to exhaustmotive fluid from the heat exchange means, a second inlet to receivefluid to be heated and a second outlet to emit the fluid which isheated; and motive fluid return means in the system including a motivefluid inlet communicating with the first heat exchanger outlet and amotive fluid outlet communicating with the boiler to return motive fluidfrom the heat exchanger to the boiler.

It is to be understood that various changes can be made by one skilledin the art in the arrangement, form and construction of the heaterassembly disclosed herein 'without departing from the scope or spirit ofthe present invention.

Referring now to the drawings which show one advantageous embodiment ofthe present invention:

FIGURE 1 shows a schematic view of a heat-powered portable heater inaccordance with the present invention;

FIGURE 2 is a vieW taken along a line passing through plane 2-2 ofFIGURE 1;

FIGURE 3 is a View partly in section taken along a line passing throughplane 33 of FIGURE 1; and

FIGURE 4 is a schematic view of one apparatus for furnishing fuel-airmixture to a burner in accordance With the present invention.

FIGURE 1 is an example of a portable heater in accordance with thepresent invention and includes a heat source in the form of an expandedmotive fluid generator 3, a fluid-responsive engine 4 driven bypressurized motive fluid, a heat exchanger 11 to receive hot motivefluid and transfer heat from such motive fluid to a second fluid to beheated, and a power transmitting device 10 driven by fluid-responsiveengine 4.

In the example of FIGURE 1, the fluid to be heated can, advantageously,be air which can be drawn from any desired source, heated by passingover heat exchanger 11, and blown into a space to be heated by fan 33 ofthe portable heat-powered heater of FIGURE 1.

Motive fluid generator 3 includes a heat source which, for purposes ofthe present example, can be a burner 17. In one example of the presentinvention the motive fluid can be vaporized as it is expanded and burner17 can be cooperatively associated with boiler 1 to transfer the heat ofcombustion generated in burner 17 to motive fluid in boiler 1. Exhaustgases from burner 17 can be exhausted in any desired manner includingblowing the exhaust gases into the space served by the heater; or intoadditional heat exchange means (not shown) to indircctly reclaim heatfrom such exhaust gases. In Example 1, an exhaust stack 22 can beprovided to exhaust combustion gases to a desired remote location.Boiler 1 is in cooperative heat-receiving relation with burner 17 andcan contain any suitable motive fluid which can be vaporized by the heattransferred from burner 1'7 It will be understood that a suitable motivefluid, for example a fluorocarbon, can, advantageously, be vaporiza'blewithin a selected temperature range dependent upon the desired operatingranges of the heater of the present invention, but, advantageously,should not be easily degradable within the range of operation.

Vaporized motive fluid can be emitted from boiler 1 by means of conduit2 at a rate dependent on the quantity of heat transferred to boiler 1and the pressure maintained in conduit 2. Flow control valve 20 can beprovided in conduit 2 to control rate of flow of vaporized motive fluidto fluid-responsive engine 4 and can be responsive to motive fluidpressure in conduit 2 by means of sensing element 20'.

It will be understood that, within the scope of the present invention,any suitable rotary fluid-responsive engine can be used; however, forpurposes of the present example, engine 4 can be a turbine. Turbine 4can receive vaporized motive fluid from boiler 1 and transform a portionof the pressure energy of the motive fluid to rotary motion by means ofshaft 9 connected to turbine 4 with the pressure of the motive fluidbeing reduced.

Reduced pressure motive fluid is exhausted from turbine 4 throughconduit 8 and the speed of rotation of turbine 4 can be controlled bycontrolling the pressure differential of the motive fluid across turbine4 as measured from inlet 5 to conduit 36 which directly communicateswith turbine outlet 8 and is downstream of bypass system 6. Bypasssystem 6 advantageously can be provided to pass pressurized motive fluidaround turbine 4 at a selected rate. The portion of the motive fluidwhich is bypassed around turbine 4, and the portion of the motive fluidwhich passes through turbine 4, are combined in conduit 36 and passed toheat exchanger 11. Flow of pressurized motive fluid through bypass 6 canbe controlled by means of valve 7 responsive through element 7 to motivefluid pressure in conduit 36 at the outlet of turbine 4. Valves 20 and 7can be cooperatively associated to control the pressure differential ofmotive fluid across turbine 4 and, therefore, the speed of rotation ofturbine 4 and shaft 7. Turbine 4 of the portable heater of the presentinvention can be designed to furnish the maximum power requirements ofthe auxiliary equipment necessary for the operation of the heater of thepresent invention, and can, advantageously, also be designed to furnishadditional useful power if desired.

As hereinbefore discussed, the pressure of the motive fluid is reducedin passing through turbine 4 and the converted energy translated torotational energy of shaft 9. Shaft 9 can be adapted to furnish powerdirectly to auxiliary elements of the present invention or alternativelycan be connected to power transmitting device 10 to transfer rotationalenergy to auxiliary elements of the fluid circulating system of theportable heater of the present invention. It will be understood thatwithin the scope of the present invention, power transmitting device 10can be of any suitable arrangement or configuration to receive power, asfrom turbine 4, and transmit useful power at selected desired speeds. Itwill be further understood that power transmitting means 10 can includemeans (not shown) for selectively changing or controlling the speedtransmitted to each of the elements of the fluid circulating system. Forpurposes of this example, power transmitting device 16 can be a geartrain connected to turbine 4 by shaft 9 and including several means fortransmitting power at different desired speed to the different elementsof the heater.

In accordance with the present invention, the motive fluid exhaustedfrom turbine 4 can be used to provide heat to the air to be heated andthe motive fluid can be returned from heat exchanger 11 to boiler 1without significant loss of heat to the atmosphere so the efliciency ofturbine 4 is not a major factor in determining the fuel efficiency ofthe system.

Heat exchanger 11 can, advantageously, be designed to heat any desiredfluid, but in the example of FIGURE 1, heat exchanger 11 can be designedto receive air. In heat exchanger 11, air is heated, motive fluid iscooled, and a portion of the motive fluid can be condensed as heat isremoved. Condensed motive fluid rejected from heat exchanger 11 iscollected in catch tank 12. While any suitable means may be employed toreturn condensed motive fluid to boiler 1, condensed motive fluidcollected in catch tank 12 can be drawn by pump 14 through conduit 13,and returned to boiler 1 through conduit 16. Shaft 15 connected to powertransmitting device 10 can be used to drive motive fluid pump 14 atdesired speed to return condensed motive fluid to boiler 11.

It is to be understood that, in accordance with the present invention,any convenient means may be used to move fluid to be heated through theheater. In the example of FIGURE 1, shaft 34, driven by powertransmitting device 10, can drive fan 33 to move air to be heatedthrough duct 32 and over heat exchanger 11. In passing air over heatexchanger 11, the air is heated by heat removed from the motive fluidand a portion of the motive fluid can be condensed as hereinbeforedescribed. Within the scope of the present invention, it will beunderstood that the air to be heated can include air which has beenrecirculated from the space served by the heater, fresh air, or acombination. FIGURE 3 indicates that heater 11 can include severalmotive fluid passes. It is to be understood, however, that within thescope of the present invention heat exchanger 11 can be of any desiredconfiguration to receive motive fluid exhausted by turbine 4, orbypassed around turbine 4, and effectively transfer heat from the motivefluid to air to :be heated.

In the example of the present invention, as shown in FIGURE 1,combustion air can be furnished to burner 17 by blower 18 which can bedriven at selected speed by shaft 21 connected to a power output frompower transmitting device 10. Fresh combustion air can be provided toblower 18 by means of a convenient duct 19 which communicates with asuitable source of air.

Within the scope of the present invention, any suitable fuel such askerosene can be used in the heater and any suitable means can beprovided to supply fuel to burner 17. In one example of a means forproviding fuel to burner 17 within the scope of the present invention,as shown in FIGURE 1, shaft 28 driven at selected speed from powertransmitting device 10 can be provided to drive fuel pump 27. Fuel pump27 can draw fuel from fuel storage tank 31 by means of conduit 29 topump fuel to burner 17 through conduit 23. Valve 24 can be provided infuel line 23 to regulate flow of fuel to burner 17, and therefore, theheat generated by burner 17 to be transferred to boiler 1. Valve 24 canregulate the flow of fuel to burner 17 in response to the temperature ofair which has been heated by heat exchanger 11, where the temperaturecan be sensed by thermal bulb 26. Alternatively, valve 24 can regulatethe flow of fuel to burner 17 in response to the temperature of motivefluid leaving heat exchanger 11, the temperature or pressure ofvaporized motive fluid leaving boiler 1, or in response to any othersuitable condition.

In accordance with the present invention, FIGURE 4 is an example ofstill another means for providing fuel to burner 17 which eliminates themechanical fuel pump. Air from blower 18 driven by shaft 21 connected topower transmitting means can be directed through aspirator 41. Aspirator41 includes dip tube 42 which extends below the surface of fuel 44 intank 43. Air can be directed through aspirator 41, so fuel is drawnthrough tube 42 into aspirator 41 to form a combustible fuel-air mixturein intake line 46. Intake line 46 can communicate with burner 17 toprovide the fuel-air mixture to burner 17 to provide heat of combustionto boiler 1 as hereinbefore described. Also, it will be understood thatwithin the scope of the present invention, any suitable means can beprovided to furnish fuel to burner 17, including, but not limited to, acompressed gaseous fuel wherein the fuel can be expanded into burner 17.

It will be understood that the method of operation of a heat-poweredportable heater, within the scope of the present invention, will bedetermined by the particular configuration and combination of elementsof the fluid circulating system. An example of a method of operation canbe described for the apparatus in accordance with the present inventionas shown in FIGURE 1.

In the example of FIGURE 1, burner 17 can be ignited to begin heatingmotive fluid in boiler 1. Fuel and combustion air can be furnished toburner 1 by manual mechanisms such as, for example, a hand-operatedblower or manual operationof vapor-responsive engine 4, or by any otherconvenient means. In one example of the present invention, as shown inFIGURE 1, a hand-operated crank 47 can be provided to furnish theinitial start-up power to power transmitting device 10 and thereby toany of the auxiliary elements of the fluid circulating sys tem ofExample 1. Valves and 7 can, advantageously, be closed in response tolow pressure in conduit 2 and turbine discharge line 36, respectively,during the startup of the heater. When the motive fluid in boiler 1 hasbeen heated to a tempertaure corresponding to a preselected pressure inconduit 2, valve 20 opens to admit vaporized motive fluid to driveturbine 4. As flow of vaporized motive fluid increases, turbine 4provides motive power to elements of the fluid circulating system of theexample of FIGURE 1, and the furnishing of manual power is no longerrequired. Also, as the flow of vaporized motive fluid to turbine 4increases, the discharge pressure of the turbine normally increases ifthe power requirements imposed on turbine 4 remain essentially constant.If the turbine discharge pressure increases in excess of a preselectedminimum, valve 7 and bypass 6 open to allow vaporized motive fluid topass around turbine 4 to reduce the pressure drop experienced by motivefluid passing through turbine 4. The rotational speed of turbine 4advantageously is controlled by controlling the pressure drop of motivefluid in the system across turbine 4 in the manner hereinbeforedescribed where the speed of rotation of turbine 4 varies directly withthe pressure dilferential in the system across turbine 4. In operationof the fluid circulating system of this example and in accordance withthe present invention, turbine 4 can receive a controlled quantity ofmotive fluid necessary for the operation of turbine 4 at a desired speedto meet the demands of a specific system. The remainder of vaporizedmotive fluid from boiler 1 can pass around turbine 4 to give up heat inheat exchanger 11 to the fluid to be heated.

Motive fluid condensed in heat exchanger 11 can be collected in tank 12.When a quantity of condensed motive fluid has been collected, motivefluid circulating pump 14 can be started to return motive fluid toboiler 1. Valve 39 in recirculating bypass 38 is closed unless thepressure in conduit 13 reaches a preselected minimum, when valve 39opens to permit motive fluid to flow back into conduit 13. Low pressurein conduit 13 can result from several conditions including the presenceof vaporized motive fluid in conduit 13. Recycling liquid motive fluidthrough bypass 38 to the inlet of pump 14 can facilitate pumpingvaporized motive fluid back to boiler 1 and maintain the flow of motivefluid through the system.

The invention claimed is:

1. An improved heat powered, portable fluid heater apparatus comprising:a motive fluid circulating system having a motive fluid supply source; aheat source within said system to expand said motive fluid, said heatsource including a motive fluid inlet and a motive fluid outlet; a fluidflow responsive rotary engine in said system to provide useful power inresponse to passage of said motive fluid through said engine, saidengine including a fluid inlet communicating with said motive fluidoutlet from said heat source, and a motive fluid outlet to exhaustmotive fluid from said engine; bypass motive fluid conduit means havingone end communicating with said motive fluid inlet of said engine andthe other end communicating with said motive fluid outlet of said engineto bypass a portion of said motive fluid around said engine; motivefluid flow control means responsive to condition of motive fluid tocontrol flow of motive fluid through said bypass motive fluid conduitmeans; power output means cooperatively joined to said engine totransmit useful power resulting from said motive fluid passing throughsaid engine; heat exchange means in said system including first inletcommunicating with said motive fluid outlet of said engine to receivemotive fluid exhausted from said engine, and a motive fluid outlet fromsaid heat exchange means to exhaust motive fluid from said heat exchangemeans; means to pass fluid to be heated through said heat exchange meansin heat transfer relation; and, motive fluid return means including amotive fluid inlet communicating with said motive fluid outlet of saidheat exchange means and a motive fluid outlet communicating with saidheat source to return motive fluid from said heat exchanger to said heatsource.

2. The apparatus of claim 1 wherein said motive fluid return meansincludes a pump driven by said power output means.

3. The apparatus of claim 1 including fluid pump means adapted to bedriven by said power output means to pass fluid to be heated throughsaid heat exchanger in heat transfer relation.

4. The apparatus of claim 1 wherein said heat source includes: a burnermeans having fuel and combustion air inlet means and an exhaust outletmeans; and a boiler disposed to receive heat from said burner tovaporize said motive fluid, said boiler being disposed intermediate saidinlet and said outlet.

5. The apparatus of claim 4 including air supply means adapted to bedriven by said power output means, to furnish combustion air to saidburner, said air supply means including an air inlet and an air outlet;and burner fuel supply pump means driven by said power output means tofurnish fuel to said burner including fuel inlet means communicatingwith a source of fuel and outlet means communicating with said fuelinlet of said burner.

6. The apparatus of claim 4 including fuel-combustion air supply meanscomprising: air supply means adapted to be driven by said power outputmeans to furnish combustion air to said burner, said air supply meansincluding air inlet means and air outlet means; and fuel aspirator meansincluding an air inlet communicating with said air outlet of said airsupply means, said fuel aspirator means further including an outletcommunicating with said burner fuel and said burner combustion air inletmeans wherein said fuel aspirator means is adapted to draw fuel intosaid aspirator in response to flow of said combustion air through saidaspirator means and mix said fuel and said combustion air in saidaspirator means.

7. An improved, heat powered, portable air heater apparatus comprising:a motive fluid circulating system; a boiler in said system to vaporize amotive fluid including a motive fluid inlet and a vaporized motive fluidoutlet; a burner in said system including fuel inlet means andcombustion air inlet means and an exhaust outlet means, said burnerbeing cooperatively disposed to transfer heat of combustion to saidboiler to vaporize said motive fluid; a rotary fluid flow engine in saidsystem to furnish useful power in response to flow of said motive fluidtherethrough, said engine including a fluid inlet communicating Withsaid boiler motive fluid outlet to receive motive fluid from saidboiler, a motive fluid outlet to exhaust motive fluid therefrom, andpower output means to transmit useful power of said engine to selectedelements of said fluid circulating system; bypass motive fluid conduitmeans having one end communicating with said motive fluid inlet of saidengine, the other end communicating With said motive fluid outlet ofsaid engine to bypass a portion of said motive fluid around said engineand motive fluid control means to control flow of motive fluid throughsaid bypass means in accordance with difference in motive fluid pressurebetween said inlet and outlet of said engine; combustion air blowermeans adapted to be driven by said power output means of said engine tofurnish combustion air to said burner, said air blower means includingair inlet means communicating with a source of combustion air andcombustion air outlet means communicating with said combustion air inletof said burner; a burner fuel pump adapted to be driven by said poweroutput means to furnish fuel to said burner including fuel inlet meanscommunicating with a source of burner fuel and a fuel out let meanscommunicating with said fuel inlet of said burner; heat exchange meansto transfer heat from said motive fluid to air to be heated including afirst fluid inlet communicating with said motive fluid outlet of saidengine to receive motive fluid, a first fluid outlet to exhaust motivefluid from said heat exchange means and means to pass a fluid to beheated over said heat exchange means in heat exchange relation; and amotive fluid return pump, to return motive fluid to said boiler fromsaid heat exchanger, said pump adapted to be driven by said power outputmeans and including an iniet cornmunicating with said outlet of saidheat exchange means and an outlet communicating with said motive fluidinlet in said boiler.

References Cited UNITED STATES PATENTS 886,079 4/ 1908 Scollard 23712.1995,154 6/1911 Kitchen 23712.1 1,047,622 12/1912 Donnelly 23'791,349,877 8/1920 Do'ble. 1,376,326 11/1921 Evans 237-121 1,476,20112/1923 Haas. 2,217,610 10/ 1940 Shannon 23 625 X EDWARD 1. MICHAEL,Primary Examiner.

